There are several reasons that wasp spray should not be used as self defense spray:
1) It is against federal law to use wasp spray in a manner that is not described on the can. Wasp spray and other pesticides are regulated by the EPA.
Although the feds have too many rules, this one should be followed because wasp spray doesn’t work anyway.
2) Wasp spray should not be used indoors. Residues may be left that are truly dangerous, but are not the type of inflammatory agent that would actually fend off an attack.
3) Those people that have been hit by wasp spray say it doesn’t really hurt and would probably not stop an attack.
Here is a sample: One reader who accidentally received a dose of wasp spray while using it around his home told me he was surprised at how little irritation he felt. “A gust of wind caused a good splash of the spray to come right back into my right eye,” he wrote. “I panicked and started to run to a source of water, only to find there was no adverse reaction at all, no more than being squirted with a water pistol. It took me at least ten seconds to get to the water, and I rinsed it off, and never felt anything from it.”
4) Wasp spray has a tight spray dispersion pattern that requires more aiming skill. In a home invasion a fogger style pepper spray would put pepper spray in a wide enough distribution pattern that the target would not avoid breathing the spray.
The idea that wasp spray is an effective deterrent against attack is basically an urban legend that probable resulted from the widespread, unfounded hype. Although wasp spray is likely mildly irritating and somewhat noxious, the effects are not debilitating enough to cause an attacker to cease an attack. The inflammatory agents in pepper spray or tear gas cause difficulty breathing and the eyes to slam shut so that the attacker can not proceed with an effective attack.
For these reasons law enforcement officials carry pepper spray, and do not carry wasp spray. Use of an insecticides on a human beings would cause widespread litigation against police officers, and would not be effective in achieving results.